Null Physics - What'd I Miss?

Explore the fascinating realm of null physics in this comprehensive lecture that delves into the theoretical foundations and recent developments in understanding null surfaces, null geodesics, and their profound implications in general relativity and quantum field theory. Examine the mathematical framework underlying null hypersurfaces and their role in describing horizons, light cones, and causal structures in spacetime. Investigate the geometric properties of null surfaces, including their intrinsic and extrinsic curvature, and discover how these structures emerge naturally in the study of black holes, gravitational waves, and asymptotic symmetries. Learn about the connection between null physics and holographic principles, exploring how information can be encoded on null boundaries and the implications for the holographic duality. Analyze the role of null infinity in understanding asymptotic flatness and the BMS group of symmetries, which has become increasingly important in modern gravitational physics. Discover recent advances in null surface dynamics, including the study of null shells, junction conditions, and the propagation of discontinuities across null hypersurfaces. Examine applications to cosmology, particularly in understanding the cosmic microwave background, primordial gravitational waves, and the large-scale structure of the universe through null cone methods. Gain insights into the mathematical tools and techniques essential for working with null geometry, including Newman-Penrose formalism, spin coefficients, and tetrad methods that simplify calculations in complex spacetime geometries.